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    Is there any more stuff I need for the galapagos islands?

    Galapagos islands are a group of 24 isolated islands to the West of ecuador who own them. These provide great examples of how increased population and introduction of exotic species can have devestating effects on other species and put them at risk of extinction. The islands are so isolated so some islandsa have species particular to them and these provide great examples of speciation.

    There are many threats to the species of Galapagos. One of these threats is increased human population increasing the need for water, sanitation and energy. For example in 1980 the population was 5,000 with around 4,000 tourists however in 2005 the population had risen to 28,000 with a massive 100,000 tourists. Also, there is the problem of habitat destruction I.e. The clearing of land for agriculture. Furthermore, there is the problem of over exploitation for resources such as overfishing and killing of tortoises for food. Furthermore, there is also the problem of introduction of non native species to the islands such as goats and cats which may interrupt fragile food webs. Also, this can lead to increased competition and the wiping out of native species I.e. Red quinine tree. There have been many measures taken over the year. For example in 1934 islands set up a wildlife sanctuary. In 1959 they created designated national park. Then in 1986, they created a Marine Reserve created. Also, a Quarantine system has been introduced to prevent exotic species getting onto islands. More than this, they have also limited the amount of places tourists can visit. Also. They have stopped fishing in some areas and have gone to the extent of culling goats and pigs to prevent the erosion of soil.
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    (Original post by slacker07906)
    Can someone explain how you do crosses? I can't do them -_-
    Do you mean like if you're given for instance CcPp × CcPp how you get the offsprings? :confused:
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    (Original post by V.sey)
    I need to confirm the difference of the terms: epistatic and hypostatic.

    In the example:

    Colourless substance------gene1-------> Red pigment-------gene 2-------> Purple pigment

    So is gene 1 the epistatic and gene 2 hypostatic?

    N.B- 'The gene which supresses the expression of another gene at a different locus is said to be epistatic, while the supressed locus said to be hypostatic.'

    Sounds simple but just to check...
    Yes, gene 1 is epistatic to gene 2 because it masks it's expression, without the red pigment = no purple since gene 2 requires it.
    Gene 2 thereforee = hypostatic, as it's the supressed locus.
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    (Original post by V.sey)
    Do you mean like if you're given for instance CcPp × CcPp how you get the offsprings? :confused:
    Yes yes yes PLEASE! I'm so bad at them you don't realise. I would really appreciate it
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    (Original post by slacker07906)
    Yes yes yes PLEASE! I'm so bad at them you don't realise. I would really appreciate it
    Have inboxed you on this one. I might not have made sense! Feel free to query
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    Genomes and Gene technologies
    Gene technologies- The lab based techniques used for handling, copying and analysing DNA and transferring DNA from one organisms to another.
    PCR (Polymerase Chain Reaction)
    PCR- A technique used to target and make multiple copies of a particular DNA fragment. It plays a role in genetic fingerprinting, identifying genes in genetic screening and genetic manipulation.
    The following process takes place:
    1. The DNA fragment is mixed with free nucleotides, a short length of DNA called a primer and a special enzyme called taq polymerase
    2. The first step is Denaturation- The temperature is raised to 95 degrees to separate the two DNA strands
    3. The second step is Annealing- The temperature is reduced to 53 degrees and primers bind to each end of the target sequence to be copied. Primers are the starting point of DNA replication
    4. The temperature is then raised to 72 degrees which is the optimum temperature of taq polymerase. The taq polymerase binds to the primers and th DNA replicates using the free nucleotides
    5. The process is repeated several times until 2n of the original DNA target sequence are produced
    Electrophoresis- In this technique fragments of DNA produced by PCR or by cutting the DNA are separated on the basis of size. It is a technique used in genetic fingerprinting, identifying faulty alleles to diagnose genetic disease (genetic screening) and sequencing genomes of different organisms.
    1. An agarose gel slab is placed in an electrophoresis tank and covered in buffer solution
    2. DNA fragments are pippeted into a well at one end of the agarose gel slab
    3. Electrical current is passed through the agarose gel slab and the negatively charged DNA fragments are attracted towards the positive electrode
    4. The shorter the DNA fragments the faster it travels through the gel
    5. The DNA fragments are separated according to size however they are still invisible
    6. To make the strands of DNA more visible, a nylon membrane is pressed against the gel and the DNA transfers up on to the membrane, however they remain invisible
    7. Radioactive gene probes are added which are short single strands of DNA which have a complementary base sequence to the DNA fragments.
    8. The gene probes bind to the DNA and an x ray film is placed against the membrane. The radioactive gene proves cause black bands to appear on the developing film. The black bands are the positions of the separated DNA fragments.
    9. Because gene probes recognise and bind to specific DNA base sequences they can be used to identify particular alleles (genetic screening) or to isolate genes for genetic manipulation. Genome studies which compare genes in different species use gene probes to identify identical sequences.
    Sequencing of the genome of an organism

    Genome- The entire base sequence of an organisms DNA, all of its genetic information

    Sequencing- A technique used to determine the order of all bases in an organisms DNA.

    Process:

    • Using restriction endonuclease enzymes the DNA is cut into short fragments of 750 base pairs long
    • The base sequence is determined in each fragment
    • Overlapping fragments are sequences and the information is put together by the computer software to generate the whole sequence
    • The entire process is automated
    Sequencing enables genome wide comparison to be made between individuals of the same species and individuals of different species.
    • It is useful to be able to compare the genome individuals of the same species as it allows to identify faulty alleles and role of genes better understood
    • It is useful to compare the genomes of individuals of different species so that evolutionary relationships can be determined. The homeobox genes of different species have been compared using sequencing techniques.
    The automated chain termination method of sequencing DNA
    1. The DNA from the organisms is obtained i.e. leaf cells are crushed in buffer and the DNA extracted and cut using restriction endonuclease enzymes
    2. DNA is placed into a reaction mixture containing free nucleotides, primers and taq polymerase. Also in the mixture is terminator nucleotides which bind to the template strand of DNA in the same way as ordinary nucletodides but stop the strand from replicating further. They are fluorescent in colour. Each of the four types (ATCG) are a different fluorescent colour
    3. The template strands are copied many times, each time thye terminator nucleotides bind at random in different positions so many different length are produced. Each fragment ends in a terminator nucleotide. The shortest fragments are only one nucleotide in length and the second shortest will be two nucleotides in length and so on until the longest fragments which will be the length of DNA being sequenced. All the fragments is known as a set of nested fragments.
    4. The fragments are passed through electrophoresis gel, the shorter the fragment the faster it travels through the gel. As the fragments reach the end the laser reads what colour the end nucleotide is
    5. The data is displayed as a series of peaks gibing a direct reading of the sequence.
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    Just a few past paper questions for you guys
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    (Original post by Waqar Y)
    I think you could breed two agouti mice to see what the phenotypic ratio of the offspring. So if two mice were CcAa x CcAa you'd get some individuals with just ccAa or ccaa which would show that some of the agouti mice were heterzygotes.


    otherwise, no idea
    I found the answer!

    Basically, you can cross the agouti mouse with an albino mouse (ccaa) and you will end up with approximately 50% offspring which will be albino mouse if the agouti was heterozygous (CcAa).
    Then if you cross the agouti mouse with albino mouse you will end up with about 100% of offspring that will be agouti if you started off with homozygous agouti mouse this time (CCAA).

    OK let's hope none of this mind- boggling Qs turn up!
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    (Original post by V.sey)
    I found the answer!

    Basically, you can cross the agouti mouse with an albino mouse (ccaa) and you will end up with approximately 50% offspring which will be albino mouse if the agouti was heterozygous (CcAa).
    Then if you cross the agouti mouse with albino mouse you will end up with about 100% of offspring that will be agouti if you started off with homozygous agouti mouse this time (CCAA).

    OK let's hope none of this mind- boggling Qs turn up!
    Makes sense ..gah got a feeling this genetic inhertiance stuff will come up too - gotta go revise in 13 mins :<
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    I've made some powerpoints if anyone wants them?

    Would really like some notes on Cellular Control and Animal Responses if anyone has any?


    EDIT - AND MEIOSIS AND VARIATION!!!
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    (Original post by yesioo)
    I've made some powerpoints if anyone wants them?

    Would really like some notes on Cellular Control and Animal Responses if anyone has any?
    I have a powerpoint on cellular control if you'd like a copy?
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    (Original post by fortunecookie)
    I have a powerpoint on cellular control if you'd like a copy?
    yes please
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    (Original post by yesioo)
    I've made some powerpoints if anyone wants them?

    Would really like some notes on Cellular Control and Animal Responses if anyone has any?
    yess pleaseeeeeee , should I PM you my email?
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    Here's a thing I made which has everything which has been on in the two papers there has been and the specimen, and a list of everything which hasn't taken directly from the specification.
    Attached Images
  1. File Type: pdf A2 Biology F215- Topics covered on previous exams (before June 2011).pdf (173.3 KB, 254 views)
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    do you reckon that given that the biotechnology module made up 54% of all the marks in the january paper, that it won't come up much on this paper???
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    (Original post by sc0307)
    yes please
    Oops read the wrong thing! Do you want to PM me your mail?
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    I have a powerpoint on cellular control if you'd like a copy?
    Please! I'll PM you my email address.

    yess pleaseeeeeee , should I PM you my email?
    Okay I only have ones on Biotechnology, The Ecosystem and Genomes?
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    (Original post by jamedz)
    Here's a thing I made which has everything which has been on in the two papers there has been and the specimen, and a list of everything which hasn't taken directly from the specification.
    Take a bow son. Cheers for this
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    URGENT
    :eek:


    Is the resit test for f215 definitely on the 13 of june while f214 is on the 23??? i messed up w/ dates before so id be grateful if someone could tell. Ill even exchange notes n past papers for info lol
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    Hi people. On Genomes and gene technologies the last specification point says discuss the ethical concerns raised by genetic manipulation of animals (including humans), plants and microorganisms. What do I exactly need to know for this? Any help would be really helpful
 
 
 
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